1. Field of the Invention
The present invention relates to wireless communications and, in particular, to a location registration method, apparatus, and system for preventing an unnecessary waste of power for a mobile terminal.
2. Description of the Related Art
In order to use the voice and data communication services such as voice call service, text messaging service, video communication service, and Internet access service, a communication terminal first connects to a network providing the corresponding service. In case of the mobile terminal, there is a network selection that is the most suitable for communication at the current location of the mobile terminal.
Typically, the mobile terminal registers with a network of a specific carrier providing the wireless communication service, and the network with which the mobile terminal registers initially is called a home network, or Home Public Land Mobile Network (HPLMN). Due to the mobility characteristic inherent to mobile terminals, such device can roam far outside of the HPLMN, as well as within the HPLMN. When the mobile terminal leaves its HPLMN, the mobile terminal can roam and register with a visited network, or Visited PLMN (VPLMN), to access for communication services. The function for the mobile terminal to access the service of another network, which is not its home network, is typically referred to as a roaming service. The roaming services can be classified into two categories: international roaming and national roaming. The international roaming refers to the ability for the mobile terminal, when in a foreign country to access a foreign service provider's network. On the other hand, national roaming refers to the ability to move from one mobile operator to another within the same country. In case of the national roaming, the mobile terminal performs a home network search periodically according to a predetermined standard rule while it is being served by the visited network. During the home network search process, the mobile terminal performs scanning periodically even when the home network does not exist at the current location. When one is outside of the country, the repeated scannings are also a complete waste of time and energy. Such a useless home network search causes unnecessary power consumption, shortening battery life and wasting resources to generate electricity to recharge batteries that have been weakened by this process.
In the meantime, maximizing power utilization efficiency is one of the key issues for battery-powered mobile terminals. With the diversification of the supplementary functions integrated in the mobile terminal, the use of mobile terminal increases and thus the efficient power management in the power-constrained mobile terminal is becoming a more significant issue. In addition, with increasing proof that the use of fossil fuels to generate electricity is contributing to the problem of global warming, there is therefore a need to develop a location registration method for a mobile terminal that is capable of preventing an unnecessary power waste especially when the mobile terminal is roaming. Considering that mobile terminal use may one day soon comprises most of the world's population, the energy savings would be significant.